Study on the permeability coefficient of weathered red sandstone soil based on laboratory constant-head permeability tests

Abstract

Weathered red sandstone soil is widely distributed across Southwest China, and its permeability is significant to the stability of slope and subgrade engineering. This study conducts a series of constant-head permeability tests on weathered red sandstone soil to examine how the permeability coefficient (k20) is affected by void ratio (e), curvature coefficient (Cc), uniformity coefficient (Cu), and particle size. The experimental results indicate that the k20 of the tested soil ranges from 1.03 × 10−4 to 1.68 × 10−2 cm/s and exhibits a strong linear positive correlation with ten to the power of the void ratio. Under conditions of consistent e and effective particle size (d10), k20 increases linearly with increasing Cc and Cu. Among the influencing factors, particle size is identified as a key factor affecting k20, with a strong linear relationship between k20 and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${d}_{10}^{2}$$\end{document}. Based on the experimental data, a multifactor predictive model integrating e, Cc, Cu, and d10 is developed. The results demonstrate that the ratio between the calculated values and the measured values generally falls within the range of 0.64 to 3.87, indicating a substantial improvement in predictive accuracy compared to traditional empirical formulas. These findings provide a theoretical basis for seepage stability analysis, drainage design, and geological disaster prevention of slopes in regions where weathered red sandstone soil is distributed.